Brazil's foreign minister yesterday warned that a police policy of shooting dead suicide bombers risked scaring innocent people as much as terrorist attackers.

Celso Amorin told the Guardian the shooting dead of Jean Charles de Menezes by police who wrongly believed he was a terrorist about to attack a train was a "summary execution". The Brazilian was shot at Stockwell tube station, south London on July 22 and his death strained relations between London and Brasilia.

Mr de Menezes' family are visiting London and said evidence they were shown yesterday from the independent investigation into the shooting made them certain police had lied to them.

Mr Amorin said: "I want to avoid strong words but this was a tragic mistake, to say the least: it was a case of summary execution of the wrong person. We owe it to the cause of human rights to be sure we are not attacking innocent people, otherwise you will be favouring the terrorists. They want to create a climate of insecurity. Now peaceful citizens are not only afraid of the bombings but also of the police."

Yesterday the brother of the shot Brazilian said the evidence he had seen from the investigation convinced him police had lied to the family. The family met with the Independent Police Complaints Commission and saw statements investigators have gathered and CCTV footage of Jean at Stockwell tube station.

Afterwards Giovani de Menezes, Jean's brother, said: "The film showed that Jean did not have suspicious behaviour. For sure they lied to the family."

The family accused police of being behind reports that he had vaulted the barrier, ran down the escalator and that he was wearing a padded jacket.

In a statement they said: "It was very distressing to see how completely relaxed and normal Jean Charles appeared, particularly in the light of statements made immediately after his death." They have demanded the resignation of the Metropolitan police commissioner, Sir Ian Blair, who yesterday joined calls for a public debate on the secretly formulated police policy of shooting dead suspected bombers.

Sir Ian said the killing of an innocent man was a "watershed moment" and that it was time to seek "broader consensus".

It emerged yesterday that six Met officers involved in the shooting have been issued with notices warning them that they may face investigation for disciplinary offences. The warnings, known as regulation nine notices, are issued to notify the officers and to protect their rights.